Olive Varieties Research Articles

Evaluation of the Antioxidant Properties and Bioactivity of Koroneiki and Athinolia Olive Varieties Using In Vitro Cell-Free and Cell-Based Assays

Olive oil and table olives are considered staples of the Mediterranean diet and have been associated with various health benefits. Literature reports that the final composition of the olive drupe is greatly affected by varietal and agronomic factors, each contributing to a different degree. To that end, the objective of the study was the evaluation of the contribution of different agronomic conditions applied to two Greek olive varieties (Koroneiki, Mastoidis) using a holistic approach of in vitro methods. The findings highlight the importance of the application of a combination of agronomic techniques for each variety, as marked by the differences found in the antioxidant radical-scavenging and reducing power assays. Furthermore, the results obtained from the measurement of redox biomarkers (GSH, ROS, TBARS) in cell lines (EA.hy926, HepG2, MKN45) treated with olive samples demonstrate the capacity of the samples to induce redox imbalance, either by protecting normal cells from damage, or by inducing oxidative damage in cancer cell lines, with the Athinolia samples exhibiting greater antioxidant potential at lower concentrations. This particular finding could have further applications in possible chemo-preventive approaches facilitated by antioxidant compounds of natural origins.

Morphological characterization and ecotypic classification of olive varie-ties in Bordj Bou Arreridj, Algeria

The aim of this research is to establish the phenotypic variation that exists in the olive varieties of Olea europaea L. in the Bordj Bou Arreridj region of Algeria. The study examined 18 olive varieties from 20 farms, focusing on the morphological characterisation of fruits, leaves, and endocarps using standard descriptors and precise measurement tools. Significant coefficients of variation were ob-served for the traits studied, indicating substantial differences among the varieties. The highest variability was found in fruit weight, with a coefficient of variation (CV) of 48.60%, while leaf length demonstrated the lowest CV at 9.77%. Principal Component Analysis (PCA) primarily distinguished three different ecotypic groups based on fruit and endocarp size and shape parameters. The Bray-Curtis similarity analysis revealed compositional similarities among some of the local variants, providing insights into their po-tential genetic relationships. Notably, the study reports the presence of the rare Leucocarpa variety, which had not been previously doc-umented in Algeria. This discovery highlights the importance of thorough regional surveys in uncovering hidden biodiversity. The findings reveal a rich agro-morphological genetic variation in olive ecotypes in the region, which is valuable for genetic conservation efforts and breeding research. This diversity could potentially be exploited to develop cultivars with improved traits such as disease resistance, oil quality, or adaptation to specific environmental condi-tions. Our classification enables targeted breeding, prioritized conser-vation, and optimized cultivation practices, supporting the devel-opment of resilient, locally-adapted varieties and the preservation of valuable genetic resources in the region's olive industry.

Effect of adding palm frond waste and spraying with tryptophan on the vegetative growth traits of olive seedlings of Manzanillo and Bash-iqi cultivars

The experiment was carried out in the plant canopy of the Department of Horticulture and Landscape Engineering/College of Agriculture, University of Kerbala, located in the Al-Husseiniyah area in Kerbala Governorate, on 11/10/2023. The experiment aimed to determine the best level of palm frond waste, along with determining the best concentration of tryptophan acid and the extent of their effect. On some characteristics of vegetative growth of olive seedlings, the experiment was carried out according to a randomized complete block design (RCBD) according to the order of the factorial experiment, with three replications. The first factor included two varieties of olive (Manzanillo and Bashiqi), while the second factor included three levels of palm frond waste (0, 3% and 6%) and the third factor included three concentrations of tryptophan acid (0, 75 and 150 ml L-1). The results showed that the Manzanillo cultivar excelled in seedling height, stem diameter, number of leaves per seedling, leaf area, relative moisture content of leaves, and the percentage of dry matter of the shoot system, with averages of (25.385 cm, 2.083 mm, 537.60 leaf seedling-1, 21.497 cm2, 77.615% and 61.071% respectively). It was also noted that the addition of palm frond waste had a significant effect, as the third level (6%) excelled in all of the aforementioned traits with averages of (28.811 cm, 2.442 mm, 611.50 leaf seedling-1, 24.648 cm2, 79.977%, and 70.957%). As for spraying with tryptophan acid, it was observed that the concentration (150 ml L-1) was superior to the same traits with averages of (24.689 cm, 2.124 mm, 529.50 leaf seedling-1, 21.351cm2, 76.760% and 61.894%). The results also showed that the interactions between the factors were significant in all the characteristics under study.

Multiple Phytophthora species associated with declining wild olive trees in Sardinia, Italy

AbstractWild olive represents one of the most iconic woody plants in the Mediterranean Basin. This slow‐growing evergreen tree is characteristic of sclerophyll vegetation, extremely tolerant to drought, salinity and diseases, thus is commonly used as rootstock for grafting cultivated olive varieties. Since 2022, extensive dieback and mortality of wild olive trees have been observed in Sardinia, Italy. Affected plants showed leaf chlorosis, wilting, defoliation, shoot blight and epicormic shoots, often associated with root rot and necroses on the feeder roots, initially associated with Phytophthora bilorbang and P. pseudocryptogea. A 2‐year study was thereafter conducted to clarify the aetiology of this unusual disease. Using a baiting technique, 10 Phytophthora taxa from three phylogenetic clades (2, 6, 8) were isolated from 53 of 87 rhizosphere soil samples collected, including P. asparagi, P. bilorbang, P. crassamura, P. inundata, P. kelmanii, P. oleae, P. pseudocryptogea, P. sansomeana and P. syringae. Additionally, some isolates that showed several polymorphisms in rDNA internal transcribed spacer (ITS) sequences compared with closely related known species are reported here as P. taxon paulensis. Pathogenicity tests on 1‐year‐old wild olive seedlings showed that nine out of 10 Phytophthora taxa significantly reduced root length of inoculated seedlings compared to controls. P. inundata and P. oleae caused the greatest reduction, while root length of seedlings inoculated with P. kelmanii did not differ from the controls. This study provides insights into the role of Phytophthora taxa in the wild olive decline in Sardinia, indicating the urgent need to expand monitoring and implement effective management strategies to mitigate the disease.

Non-invasive detection of pesticide residues in freshly harvested olives using hyperspectral imaging technology

Pesticides play a crucial role in boosting the overall yield and productivity of agricultural produce by controlling pests, insects, and various plant diseases. However, excessive use of pesticides has led to contamination of food products and water bodies, as well as disruption of ecological and environmental systems. Global health authorities have set limits for pesticide residues in individual food items to ensure the availability of safe foods in the supply chain and to assist farmers in developing optimal agronomic practices for crop production. In Spain, specifically regarding olive cultivation, the Ministry of Agriculture, Fisheries, and Food establishes a safety period that farmers must observe from the application of the pesticide until the fruit is harvested. This period ensures that the batch of olives will comply with the maximum residue level allowed. This article proposes a methodology based on hyperspectral imaging to detect whether the olives have been sprayed with pesticide products and, if so, when the spraying occurred. The proposed methodology operates at the pixel level, where each pixel of the hyperspectral image is an instance. The pesticides evaluated were Diflufenican, Oxyfluorfen, Deltamethrin, λ-Cyhalothrin, and Tebuconazole. The results are promising and the success rates achieved over 80% accuracy for most pesticides in controlled laboratory conditions, with individual performance varying according to each pesticide's chemical properties and stability on the olive surface. While the results are promising, the scalability of this approach for larger and more diverse batches of olives requires validation under field conditions, where variations in environmental factors, olive variety, and ripeness may impact the detection accuracy. Furthermore, the study highlights key wavelengths around 750 nm and 550 nm as effective discriminators, suggesting potential for cost-effective, simplified imaging systems. Although hyperspectral imaging shows potential as an accessible, in-line monitoring solution for cooperative use, further analysis of implementation costs is recommended to confirm its feasibility on an industrial scale.

Phenylpropanoid metabolism may dominate the black spot resistance of Chinese olive (Canarium album)

The black spot of Chinese olive (Canarium album) seriously reduces the appearance quality and economic value of this fruit. In this study, we identified a black spot resistant variety called ‘Shuanghuxiang’ (CS) and a susceptible variety called ‘Yunzhi’ (CY), and investigated the underlying resistance mechanisms. Paraffin sectioning analysis indicated greater susceptibility of CY fruit epidermis to breakage post black spot infection compared to CS, with SEM analysis showing lower pathogen presence on CS fruits. These results revealed that the variation in black spot resistance could be attributed to differences in fruit epidermis structure and antimicrobial properties. Through conjoint transcriptomic and metabolomic analyses, we observed enrichment of genes (particularly CaPAL1 and Ca4CL1) and metabolites (particularly trans-cinnamate, ferulic acid and sinapate) related to phenylpropanoid metabolism in CS. These results indicated that the phenylpropanoid metabolism may play a crucial role in black spot resistance. This study provides theoretical basis and valuable material for the breeding of resistant varieties of Chinese olive.

Genome-Wide Identification and Characterization Thaumatin-like Protein (TLP) Genes in Wild Olive (Olea europaea var. sylvestris)

The wild olive tree (Olea europaea var. sylvestris) is the ancestor of all olive varieties, displaying remarkable adaptability to diverse climatic conditions and soil types. This iconic tree of the Mediterranean Basin stands out for its ability to withstand environmental stresses, such as water scarcity and temperature variations, playing a crucial role in the ecology, economy, and culture of the region. In this study, 42 TLP genes were characterized in the wild olive tree, distributed across 14 chromosomes and nine scaffolds. In silico analysis revealed the presence of domains associated with antifungal activity in some sequences, indicating their potential role in pathogen resistance. The structural diversity of OeTLP genes was explored through multiple alignments, conserved motifs and phenetic analysis. Correlation was observed between phenetic diversity, genetic structure, and motif patterns, suggesting different functions among OeTLP groups. Additionally, the distribution of exons and introns in the pheneticc tree provided further insights into the evolution of these genes. Comparative modeling of OeTLPs unveiled three-dimensional models with good structural quality and distinctive surface charge characteristics. This study provides a comprehensive understanding of the physicochemical, structural, and phenetic features of TLP genes in Wild Olive, contributing to knowledge about this species' response to environmental stresses and pathogens.

Electrical Impedance Spectroscopy: A Tool for Determining the Harvesting Time of Olive Fruit

The harvesting time of olive (Olea europaea L.) fruit, which significantly affects the characteristics of virgin olive oil, is mainly determined empirically based on the fruit’s skin color. Developing objective methods such as electrical impedance spectroscopy (EIS) for assessing ripeness is essential. This study aimed to explore the potential of EIS as a rapid and objective technique for detecting the harvesting time of olives. Olive fruits from two varieties, ‘Picholine’ and ‘Buža momjanska’, were harvested in two periods and sorted into four color groups. EIS was applied to each color group to establish a relationship between fruit color and electrochemical properties. The distance of the coordinate at the top of the circular arc of the Cole–Cole plot from the origin (LTO) indicated tissue degradation. The LTO values varied depending on the olive variety, fruit color, and harvest date. The LTO values decreased from green to black fruits in both varieties, indicating textural changes in the olive fruit tissue. This study contributes to the knowledge and understanding of the electrical properties of olive fruit tissue during ripening. EIS shows potential as an innovative tool for determining the harvesting time of olives and for ‘in-field’ olive ripeness assessment.

Characterization of Some Olive Varieties Consumed without Pre-Treatment: Naturally Debittered Olives in Türkiye

In table olive production it is necessary to remove oleuropein by brine or dry salting method because it gives bitterness. However, some olive varieties such as Throuba Thassos-Greece, Djemali-Tunisia can be consumed without any de-bittering process. Some olives in Türkiye are also consumed without any pre-treatment and these are Kilis Yağlık, Butko, Hurma (Erkence cv.), and Nizip Yağlık olives. These naturally de-bittered olives were aimed to be characterized in this research. The lowest moisture content was determined for Kilis Yağlık (6.84%) and the highest moisture content was determined for Butko (50.01%). The oil and protein content of the samples was between, 16.66-68.46% and 0.19-18.13%, respectively. Total phenolic content (mg GAE/100g) of Kilis Yağlık, Butko, Hurma and Nizip Yağlık olive varieties were determined as 458.87, 152.09, 109.73, 234.33, respectively. The lowest antioxidant capacity was determined for Butko and the highest value was determined for Kilis Yağlık. The hardness values of the olives were found between 677.44-3688.06 (g). The L*, a*, b* values of olive samples were found between 26.14-32.05, 2.02-4.78, 2.37- 7.18, respectively. Highest oleic was determined for Hurma, highest linoleic acid was determined for Butko whereas the highest linolenic acid was determined for Nizip Yağlık. Volatile component analysis results of olives showed that 24, 23, 16 and 17 volatile components were detected in Kilis Yağlık, Butko, Hurma and Nizip Yağlık olives, respectively.

A New Validated Method for Rapid Determination of OLEU Concentration in Dietary Supplements: Comparison with Total Phenol Content and Antioxidant Activity

The market for olive leaf dietary supplements is expanding rapidly and is valued at $437.15 million today. However, information on the control of these products is sketchy and the origin and variety of olives are rarely stated. The aim of this research was to validate a simple and rapid screening method for oleuropein determination in olive leaf dietary supplements. A matrix blank was prepared by removal of oleuropein from a mixture of dietary supplements and the matrix was then spiked with known concentrations to create a spiked matrix calibration curve in the range 5 - 40% oleuropein. Five replicate extractions and analyses of the matrix standards were carried out over 10 days. Precision was less than 6% RSD and linearity was demonstrated by the Fischer test. Extraction recovery was > 90% and there was a strong linear relationship between authentic and matrix standards. All tested products conformed to the label claim which was strongly correlated with total polyphenols measured by the Folin-Ciocalteau method. Antioxidant activity was measured by the DPPH assay and was found to be strongly correlated with total phenol content and oleuropein concentration.

Analysis of Genetic Diversity of Some Olive Cultivars Olea Europoea L. Using ISSR, SSR

In the current investigation, the genetic relations, and the genetic dimension of seven olive varieties (Olea europaea L.) were identified using, ISSR, and SSR markers. The study involved uses leaves from different samples for DNA extraction. The DNA amount ranged from 150 to 400 micrograms with purity ranging between 1.6 to 1.9. Agarose gel electrophoresis is applied to evaluate PCR reaction success. The ISSR marker, which used 4 primers, showed different results for the multiplication. Various bands were observed that differed from each other, resulting in a total of 93 bands - 2 general and 91 different. The primer also distinguished unique bands, with 4 unique bands and 7 absent bands. The primer with the highest molecular size (1500bp) was UBC-817, while the lowest molecular volume (200bp) was observed in the UBC-826 primer. The marker results indicated that the two types, Suranie (3) and Frantoio (4), had the lowest hereditary dimension of (0.030). The Frantoio and Santacatrina varieties showed the highest genetic difference, with a value of 0.622. According to the genetic relationship analysis, there were three main groups. The first group consisted of a single category (5), while There were two subgroups in the second group, B1 and B2. Subgroup B1 had only one category, while the rest of the categories were in Subgroup B2.. Even though these markers use different mechanisms to detect variance and genome coverage, they complement each other. Moreover, five SSR markers were used in this study to describe seven olive cultivars and analyze their genetic relationship. Four out of five primers showed positive results, while one was not present. The SSR markers were effective in identifying the similarity of collected species, as they are specialized indicators ISSR markers.

Optimization of Different Extraction Methods for Phenolic Compound Verbascoside from Chinese Olea europaea Leaves Using Deep Eutectic Solvents: Impact on Antioxidant and Anticancer Activities.

Chinese Olea europaea leaves, rich in verbascosides, were extracted using ultrasound-assisted extraction (UAE) and wall-breaking extraction (WBE) with deep eutectic solvents (Optimal UAE: 55 min, 200 mL/g liquid-solid ratio, 20% moisture, yielding 206.23 ± 0.58 mg GAE/g total phenolic content (TPC) and 1.59 ± 0.04% verbascoside yield (VAY); Optimal WBE: 140 s, 210 mL/g, 30% moisture, giving 210.69 ± 0.97 mg GAE/g TPC and 1.33 ± 0.2% VAY). HPLC analysis showed that young leaves accumulated higher TPC and phenolic compounds. Among the five olive varieties, Koroneiki and Chemlal showed the highest TPC in UAE, while Arbosana and Chemlal excelled in WBE. WBE yielded a higher TPC and rutin, whereas UAE marginally increased other phenolics. Additionally, the DPPH• assay showed that WBE-extracted verbascoside-rich extracts (VREs) of Chemlal exhibited high antioxidant activity (EC50 of 57 mg/mL), but Koroneiki-VREs exhibited lower activity against the ABTS•+ radical (EC50 of 134 mg/mL). Remarkably, the UAE/WBE-extracted Chemlal-VREs promoted the normal esophageal Het-1A cell line at 25 μg/mL for 24 h; yet, the esophageal cancer Eca-109 cells were sensibly inhibited, especially at 50 μg/mL; and the cell viability decreased dramatically. The results confirmed WBE as a relatively efficient method, and the Chemlal variety may be an excellent source of verbascoside.

Development of a rapid and fruit-saving method for fatty acid composition analysis in olive: a comparative study on 27 cultivars.

Fatty acid composition is an essential aspect of the qualitative assessment of olive oil. A method for evaluating and trending fatty acid composition of olive varieties directly from a limited amount of drupes, has been proven reliable in comparison with traditional oil analysis. No significant difference was detected between the two methods for the 27 cultivars tested, despite presenting decidedly different acid compositions. The results obtained, crossed with those of oil yield, can represent a useful resource to set the harvest calendars by choosing the most suitable time for the production of superior quality oils and for reducing the risk of pathogen infections or pest attack. For three cultivars, the acid composition was evaluated during three ripening phases (green, veraisoned and veraisoned to black). The different behaviors suggest it is the genotype that determines this -still little known- physiological trait in olive. An interesting finding was that the oils from drupes harvested in August showed linolenic acid values higher than the limit (1.00%) set in the international standards for the classification of olive oils, requesting further investigation.

Characterisation and traceability of extra virgin olive oil and table olive of Azapa variety marketed in Chile using Microsatellite Molecular Markers

Chile has two certified origin olive products: Extra-Virgin Olive Oil (EVOO) from Huasco valley and the Azapa variety table olive from the Azapa valley. However, efficient methodologies are needed to determine the varieties and raw materials involved in the end products. In this study, we assessed the size of alleles from ten microsatellites in 20 EVOOs and in leaves and fruits of 16 olive varieties cultivated in Chile to authenticate their origins. The identification of varieties relied on specific allele sizes derived from microsatellites markers UDO99-011 and DCA18-M found in leaves and fruit mesocarp. While most Chilean single-variety EVOOs matched the variety declared on the label, inconsistencies were observed in single-variety EVOOs containing multiple varieties. Our findings confirm that microsatellites serve as a valuable as diagnostic tools for ensuring the quality control of Geographical Indication certification for Azapa olives and EVOO with Designation of Origin from Huasco.

Bioactive Compounds in the Oils of the Autochthonous Slovenian Olive Varieties 'Buga', 'Črnica' and 'Drobnica'.

The adaptation of autochthonous olive varieties to local soil and climatic conditions can lead to a unique chemical composition and characteristics of olive oils that may differ from the generally accepted quality standards set out in the International Olive Oil Council strategy documents and EU regulations. Therefore, the fatty acid composition, biophenol, tocopherol, sterol and triterpenic dialcohol content and composition of the autochthonous Slovenian olive varieties 'Buga', 'Črnica' and 'Drobnica' were studied for a three-year period with the aim of valorising the characteristics of the three olive varieties. Standardised and accredited analytical methods in accordance with SIST EN ISO/IEC 17025:2017 were applied. The results of the investigation showed that the highest average amount of oleic acid (75.75%) was found in the oils of the 'Črnica' variety, followed by the 'Drobnica' (72.06%) and the 'Buga' (68.73%). All three varieties are a good source of total biophenols ('Buga' 616 mg/kg, 'Drobnica' 569 mg/kg and 'Črnica' 427 mg/kg) and α-tocopherol ('Buga' 378 mg/kg, 'Drobnica' 279 mg/kg, and 'Črnica' 243 mg/kg). 'Buga' and 'Drobnica' are characterised by high amounts of total sterols, 2468 mg/kg and 2391 mg/kg, respectively, while 'Črnica' oils, in comparison, showed a lower average value of total sterols (1351 mg/kg). Due to their exceptional chemical composition, 'Buga', 'Črnica' and 'Drobnica' show great potential for the further cultivation and valorisation of traditional olive oil production in the region, thus contributing to the preservation of biodiversity and local traditions. The quality parameters of olive oil from the autochthonous Slovenian olive varieties 'Buga', 'Črnica' and 'Drobnica' also fulfil the limits for extra virgin olive oil according to the Commission Delegated Regulation (EU) 2022/2104, despite local climatic influences. However, accelerated growth due to climatic changes affecting early harvest can lead to them falling outside these limits, which was observed in particular for the 'Buga' variety in terms of the linoleic acid content. This study emphasises the importance of timing the harvest to achieve optimum maturity and meet EU quality standards, taking into account the genetic makeup of the varieties and their response to the current climatic conditions.

Usefulness of the 1H NMR Multisuppression Approach for the Global Characterization of Monovarietal Extra-Virgin Olive Oils.

Extra-virgin olive oil (EVOO) is one of the most appreciated vegetable oils worldwide, but its high price makes it prone to suffer adulteration with lower quality oils. Therefore, it is important to have methodologies able to study EVOO composition as a whole in a simple and fast way, in order to guarantee its quality and safety. For this purpose, in this study, commercial samples of five Spanish olive cultivars (Arbequina, Arroniz, Cornicabra, Hojiblanca, Picual) were studied by Proton Nuclear Magnetic Resonance (1H NMR) spectroscopy, using standard and multisuppression pulses. The aim was to explore the possibility of 1H NMR use to characterize in a single run and in a global way the composition of these monocultivar oils, regarding not only their main components (fatty acids supported on triglycerides) but also minor ones (squalene, sterols, diterpenic wax esters of phytol and geranylgeraniol, phenolic and secoiridoid derivatives, like tyrosol, hydroxytyrosol, oleacein, oleocanthal, and lignans, among others, and aldehydes). The use of univariate and multivariate statistical analyses confirmed the presence of compositional features that were specific to some olive varieties. The Arbequina and Arroniz oils showed the most characteristic features that allowed for clearly differentiating them from the others. In contrast, the discrimination between the Cornicabra, Hojiblanca and Picual oils was not so easily achieved.

Extraction of Oil from Different Cultivars of Olive Fruits and Their Profiling by Gas Chromatography

Olive varieties differ from each other in terms of their morphological attributes, such as leaf size and shape, fruit size, color, texture and shape. These differences arise as a result of combination of different genotypic composition as the variable environmental conditions. The genotypic and phenotypic differences arising in plants are further translated to the level of the fruits, as a consequence of which, olive fruits from different cultivars yield different kinds of olive oils. The current study shows variable oil parameters of olive oil harvested from four different cultivars of oils, namely, [Arbequina (A), Barnea (B), Cortina (C), Koronoiki (K)] which were collected from two different sites, Napasar (N) and Lunkaransar (L), Bikaner (Rajasthan) and furthermore evaluate the variation in oil parameters (oil content as well as fatty acids present in oils) of different olive cultivars. The results of the study show that oil from all the varieties differed from each other in terms of colour as well as fatty acid profile. All these variations were attributed to the difference in genotype of different olive cultivars as well as variable metrological conditions coupled with different physico-chemical attributes of water and soil in both Napsar and Lunkaransar.

Nutrient and Bioactive Fraction Content of Olea europaea L. Leaves: Assessing the Impact of Drying Methods in a Comprehensive Study of Prominent Cultivars in Morocco.

This study explores the potential of olive leaves, long integral to Mediterranean traditional medicine, as a rich source of valuable compounds. The challenge lies in their considerable water content, hindering these compounds' full valorization. Four drying methods (air-drying, oven-drying, freeze-drying and solar-drying) were investigated for their impact on nutrient and bioactive compound content in the leaves of four olive varieties ("Arbequina", "Koroneiki", "Menara" and "Picholine Marocaine") cultivated in Morocco. In their fresh state, "Picholine Marocaine" exhibited the highest protein levels (6.11%), "Arbequina" had the highest phenolic content (20.18 mg gallic acid equivalents/g fresh weight (FW)), and "Koroneiki" and "Menara" were highest in flavonoids (3.28 mg quercetin equivalents/g FW). Specific drying methods proved optimal for different varieties. Oven-drying at 60 °C and 70 °C effectively preserved protein, while phenolic content varied with drying conditions. Air-drying and freeze-drying demonstrated effectiveness for flavonoids. In addition, an analytical approach using high-performance liquid chromatography and diode array detection (HPLC-DAD) was applied to investigate the effects of the different drying methods on the bioactive fraction of the analyzed samples. The results showed qualitative and quantitative differences depending on both the variety and the drying method used. A total of 11 phenolic compounds were tentatively identified, with oleuropein being the most abundant in all the samples analyzed. The freeze-dried samples showed the highest content of oleuropein in the varieties "Arbequina" and "Picholine Marocaine" compared to the other methods analyzed. In contrast, "Koroneiki" and "Menara" had higher oleuropein content when air dried. Overall, the obtained results highlight the importance of tailored drying techniques for the preservation of nutrients and bioactive compounds in olive leaves.

Molecular Traceability Approach to Assess the Geographical Origin of Commercial Extra Virgin Olive Oil.

Extra virgin olive oil (EVOO) is a precious and healthy ingredient of Mediterranean cuisine. Due to its high nutritional value, the interest of consumers in the composition of EVOO is constantly increasing, making it a product particularly exposed to fraud. Therefore, there is a need to properly valorize high-quality EVOO and protect it from fraudulent manipulations to safeguard consumer choices. In our study, we used a straightforward and easy method to assess the molecular traceability of 28 commercial EVOO samples based on the use of SSR molecular markers. A lack of correspondence between the declared origin of the samples and the actual origin of the detected varieties was observed, suggesting possible adulteration. This result was supported by the identification of private alleles based on a large collection of national and international olive varieties and the search for them in the molecular profile of the analyzed samples. We demonstrated that the proposed method is a rapid and straightforward approach for identifying the composition of an oil sample and verifying the correspondence between the origin of olives declared on the label and that of the actual detected varieties, allowing the detection of possible adulterations.

Effects of arbuscular mycorrhizal fungi in the rhizosphere of two olive (Olea europaea) varieties Arbequina and Barnea under water deficit conditions.

One strategy to improve olive (Olea europaea ) tree drought tolerance is through the symbiosis of arbuscular mycorrhizal fungi (AMF), which helps alleviate water deficit through a combination of morphophysiological effects. Cuttings of olive varieties Arbequina (A) and Barnea (B) were grown with (+AMF) or without (-AMF) inoculum in the olive grove rhizosphere soil. One year after establishment, pots were exposed to four different water regimes: (1) control (100% of crop evapotranspiration); (2) short-period drought (20days); (3) long-period drought (25days); and (4) rewatering (R). To evaluate the influence of AMF on tolerance to water stress, stem water potential, stomatal conductance and the biomarkers for water deficit malondialdehyde, proline, soluble sugars, phenols, and flavonoids were evaluated at the end of the irrigation regimes. Stem water potential showed higher values in A(+) and B(+) in all water conditions, and the opposite was true for stomatal conductance. For proline and soluble sugars, the stem water potential trend is repeated with some exceptions. AMF inoculum spore communities from A(+ and -) and B(+ and -) were characterised at the morphospecies level in terms of richness and abundance. Certain morphospecies were identified as potential drought indicators. These results highlight that the benefits of symbiotic relationships between olive and native AMF can help to mitigate the effects of abiotic stress in soils affected by drought.